But Mr Blunkett said it was "patronising" to suggest immigrants may not be able to improve their English and added disabled people would be exempt.

He also denied the move would harm Britain's diversity.

Conservative home affairs spokesman Humfrey Malins said he backed the
tests "in principle" but would study the proposals carefully.

Mr Blunkett put forward the citizenship proposals in 2002 as part of the Home Office's flagship nationality and immigration legislation.

The two key requirements of the scheme were that new citizens should have a "sufficient understanding of English, Welsh or Scots Gaelic" and a "sufficient understanding of UK society and civic structures".

'Everyday needs'

The home secretary said both elements should improve integration and a sense of belonging, rather than hinder the process of naturalisation.

The system was drawn up by a team of citizenship and nationality experts led by Professor Sir Bernard Crick, Mr Blunkett's former university tutor.

In its interim report published earlier in the year, Sir Bernard's team recommended new citizens should formally learn about key elements of British life and everyday needs.

Crick was a university tutor of Blunkett's

It also recommended practical studies to progressively improve language skills for daily life, with a target to improve rather than reach a certain standard.

Prof Crick said the exam at the end of the course would be on a similar level to a driving test.

"We are not trying to define Britishness, we are trying to define what people need to settle in effectively," he told Today.

"One of the big objects of this report... is integration in the sense of people feeling secure in their own identities, but also sharing a wider identity."

A handbook will include all the required knowledge for passing the test.

Proposals for special civic ceremonies welcoming those being naturalised have yet to be finalised.

A total of 120,000 immigrants a year win British citizenship, after living in the UK for five years.